Comparative clinical study between zirconium-ceramic and metal-ceramic fixed rehabilitations.

Objective: This research represents a comparative study between metal-ceramic and zirconium-ceramic fixed prosthesis; it evaluates the maintenance of the prosthesis mechanical, functional and aesthetic characteristics few years after functional implantation. Methods: The study participants were 46 in total: 26 rehabilitated with a metal-ceramic fixed prosthesis and the remaining 20 with a zirconium-ceramic prosthesis. 13 male patients in the age range of 36-63 years and 13 female patients in the age range of 33-83 years (average age of 49.5 years) composed the metal-ceramic group. 11 male patients in the age range of 39-60 years and 9 female patients in the age range of 22-59 years (average age of 54.1 years) formed the zirconium-ceramic group. The study population only included patient with fixed prosthesis on three mandibular elements and absence of first inferior molar. The abutment teeth were both natural and vital or treated with endodontics: in any case, no periapical or periodontal lesions were present; at the beginning of the procedure, the patients displayed a healthy periodontium, no sign of bone reabsorption, stable occlusion and natural opposing dentition. Patients showing bruxism and poor oral hygiene were excluded from the study. All the participants gave their written informed consent. Results: The cases treated with metal-ceramic prosthesis resulted “excellent” in 57.14% of cases, “acceptable” in 39,16% of cases and only 3.70% “to remake”. The results regarding the patient treated with zirconium-ceramic prosthesis during the entire follow-up period were “excellent” in 52.0% of cases, “acceptable” in 44.0% of cases, “to remake” in 4.0% of the cases. Conclusions: Our study demonstrates that none of the 28 metal-ceramic cases and none of the 25 zirconium-ceramic cases has been subject to substructure fractures. Both methods demonstrated a seven-year extremely high survival rate, with almost overlapping percentages of 96.3% for metal-ceramic and 96,0% for zirconium-ceramic. The confronted methods demonstrated to be adequate for the target rehabilitative therapy. The masticatory load is greatly tolerated by the respective substructures, which did not show any inclination to fracture.